Wire Choice
Kirk Fraser
Posts: 364
I've been having trouble with wires connecting my propeller to a sensor. My local PUD says copper wires get brittle, breaking more often than aluminum wires. For electronics, what is the wire of choice?
Based on my general knowledge, I would think a copper coated soft steel wire ought to be conductive, stong, and flexible to maximize endurance when manipluating the boards or applications where there's a lot of flexing.
Any specific links to buy reliable wires? Thank you.
Based on my general knowledge, I would think a copper coated soft steel wire ought to be conductive, stong, and flexible to maximize endurance when manipluating the boards or applications where there's a lot of flexing.
Any specific links to buy reliable wires? Thank you.
Comments
What's a PUD?
I believe it is Public Utility Department.
I once used stranded copper extension cord to wire a switch for a burglar alarm through a door so locking the key would activate it. Unfortunately even with plenty of slack the flex eventually broke the wire in a few months. My current Propeller application has much less flex but apparently my own handling of the boards was enough to break a solid Cat-5 wire or two.
So what do they use for flat ribbon cable to the print head in printers with movable heads?
Generally speaking, a stranded copper wire is flexible up to some point where it's made non-flexible by soldering it to something, or trapping it in some way such that it makes a sharp bend. For best reliability, use crimped connectors (don't try to "improve the reliability" by soldering them) and any place the wire has to bend a lot put a loop, never a sharp corner. Line cord isn't the best example of copper wire because the cheap plastic insulation can get stiff, crack, and then that crack will force the copper to bend sharply at that point which can cause it to fail. Even then, I have devices with line cords that have been bending without problems for many years.
One addition point. Instead of asking the power utility, which has different problems than sensor wiring, ask an alarm installer or the telephone company what they use.
This is due to several reasons
A. flexing
B. corrosion
C. lack of adequate insulation
Of course a PUD would mention aluminum as it is used in power transmission cables, but due to the high resistance of aluminum oxide forming at the ends, it is rather infamous for causing electrical fires in house wiring. You can't easily solder it, and it must be properly prepared and coated with anti-oxidant to work well.
In other words, forget aluminum.
Copper is generally the simplest and most cost effective to use. Some components -- such as axial resistors - are indeed soft iron that is plated with copper. But nearly all small diameter cables are constructed from copper alone.
Again, the PUD may be referring to high tension transmission cables that require a steel cable to support the huge distances between towers and the outside is coated with copper.
In the world of tiny devices -- people often try to use silver and gold as alternatives. Silver forms an oxide that creates all sorts of problems similar to aluminum, but gold and some other precious metals do not. Gold is used on the internal construction of many chips is extremely tiny wires. But you will likely never own the machinery to wire such devices.
If you absolutely must have flex in a connection, there are a lot of remedies -- strain relief devices, coiled flexible cords, and more. IT is all about the contruction details, not about changing to another metal.
In sum, stick with copper unless you have an excellent reason not to. And pay attention to your connections to make sure they are 100% effective. About the only other electrical conductor I use in some cases is brass as a heavy buss material.